Hi - I'm experiencing a "CUDA error: Launch failed in cuCtxSynchronize()" error with the [[ http://blenderartists.org/forum/attachment.php?attachmentid=297482&d=1395468047 | .blend ]]posted at the following BA thread:
http://blenderartists.org/forum/showthread.php?331149-The-new-Cyles-GPU-2-70-Benchmark&p=2605009&viewfull=1#post2605009
Information copied here for convenience:

3x GeForce GTX Titan (Driver 335.23 WHQL latest as of this post)
Windows 8.1 64 bit
Blender 2.70 64 bit (Official released)

GPU SLI Disabled (how I normally render)
When I open and press F12, render finishes in 1 second with blank render output
When I which to Rendered view in the 3D View, "CUDA error: Launch failed in cuCtxSyncronize()"
GPU SLI Enabled (for troubleshooting)
Hard system lock up requiring a reset - This is the first time I have seen this behavior
CPU Render:
Render completes in 5:34.77 with only Tiles setting change to 16

335.23 is the "stable" tested driver release. I don't see a later beta release at this time. I've not seen any problems with GPU rendering otherwise.
GPU render of same file using different PC and Blender 2.70 64 bit and video different driver works fine.

Apologies if this is actually unrelated to the parent bug report